function ScreenSaver(settings) {

  this.settings = settings;

  this.nTimeout = this.settings.timeout;

  document.body.screenSaver = this;
  // link in to body events     
  document.body.onmousemove = ScreenSaver.prototype.onevent;
  document.body.onmousedown = ScreenSaver.prototype.onevent;
  document.body.onkeydown = ScreenSaver.prototype.onevent;
  document.body.onkeypress = ScreenSaver.prototype.onevent;

  var pThis = this;
  var f = function () { pThis.timeout(); }
  this.timerID = window.setTimeout(f, this.nTimeout);
}
ScreenSaver.prototype.timeout = function () {
  if (!this.saver) {
    console.log('时间到了')
    window.history.back(-1)//无动作跳转地址  
  }
}
ScreenSaver.prototype.signal = function () {
  if (this.saver) {
    this.saver.stop();
  }

  window.clearTimeout(this.timerID);

  var pThis = this;
  var f = function () { pThis.timeout(); }
  this.timerID = window.setTimeout(f, this.nTimeout);
}

ScreenSaver.prototype.onevent = function (e) {
  this.screenSaver.signal();
}